Control apparatus for a switching device with a pull-in coil and/or a holding coil and method for controlling the current flowing through the coil

Abstract

A control apparatus for a switching device including a contactor drive and a coil includes a pulse width-controlled switching mechanism connected to a coil and a control unit connected to the switching mechanism. The control unit is configured to generate a control signal having an adjustable pulse width and set the adjustable pulse width as a function of an input voltage signal so as to maintain a current through the coil approximately constant. The control unit is further configured to determine a voltage of the control apparatus by determining an instantaneous coil voltage of the coil and adjusting a current pulse width modulation turn-on time in accordance with the instantaneous coil voltage using at least one data processing unit.

1 - 24 . (canceled) 
     
     
         25 . A control apparatus for a switching device including a contactor drive and a coil, comprising:
 a pulse width-controlled switching mechanism connected to a coil; and   a control unit connected to the switching mechanism, the control unit configured to generate a control signal having an adjustable pulse width and set the adjustable pulse width as a function of an input voltage signal so as to maintain a current through the coil approximately constant, the control unit configured to determine a voltage of the control apparatus by determining an instantaneous coil voltage of the coil from the input voltage signal and based on a pulse width modulation time, and adjusting a current pulse width modulation turn-on time in accordance with the instantaneous coil voltage using at least one data processing unit configured to compare the instantaneous coil voltage of the coil with a predetermined coil voltage setpoint stored in the control unit so as to determine the current pulse width modulation turn-on time for the control signal of the control unit.   
     
     
         26 . The control apparatus of  claim 25 , wherein the coil includes at least one of a pull-up and a holding coil. 
     
     
         27 . The control apparatus of  claim 25 , wherein the predetermined coil voltage setpoint is not greater than a minimum value of the input voltage of the control apparatus. 
     
     
         28 . The control apparatus of  claim 25 , further comprising a voltmeter configured to measure the voltage of the control apparatus. 
     
     
         29 . The control apparatus of  claim 25 , further comprising a scanning device configured to scan the input voltage signal. 
     
     
         30 . The control apparatus of  claim 25 , wherein the pulse width-controlled switching mechanism comprises a switching transistor. 
     
     
         31 . The control apparatus of  claim 30  wherein the switching transistor includes a field effect transistor. 
     
     
         32 . The control apparatus of  claim 25 , further comprising a pulse generator configured to generate the control signal having the adjustable pulse width. 
     
     
         33 . The control apparatus of  claim 25 , wherein the at least one data processing unit comprises a microcontroller. 
     
     
         34 . The control apparatus of  claim 27 , wherein the control unit comprises an impedance converter configured to adapt an impedance of the voltmeter to an impedance of the control unit. 
     
     
         35 . The control apparatus of  claim 34 , wherein the impedance of the voltmeter is higher than the impedance of the control unit. 
     
     
         36 . The control apparatus of  claim 35 , wherein, the impedance converter comprises at least one operational amplifier. 
     
     
         37 . The control apparatus of  claim 27 , wherein the at least one data processing unit comprises an input side having an analog-digital converter configured to convert an analog measuring signal of the voltmeter into a digital signal, and wherein the at least one data processing unit is configured to further process the digital signal. 
     
     
         38 . The control apparatus of  claim 25 , further comprising a rectifier circuit configured to rectify an alternating voltage input to the control apparatus. 
     
     
         39 . The control apparatus of  claim 25 , further comprising a filter circuit configured to filter alternating voltage portions from the input signal of the control apparatus. 
     
     
         40 . The control apparatus of  claim 25 , wherein a period between two control procedures is not greater than 150 μs. 
     
     
         41 . A switching device having an integrated control apparatus comprising:
 a pull-in or holding coil;   a pulse width-modulated switching mechanism; and   a control unit connected to the switching mechanism and configured to generate a control signal having an adjustable pulse width, wherein the control unit determines the pulse width of the control signal as a function of an input voltage signal of the control unit so as to keep a current through the coil approximately constant.   
     
     
         42 . A method for controlling a current flowing through a coil of a switching device having a switching mechanism, comprising:
 a) receiving an input voltage to the switching device; and   b) determining a pulse width modulation signal as a function of a predetermined voltage setpoint of the coil voltage so as to control the switching mechanism so as to maintain a current approximately constant through the coil of the switching device.   
     
     
         43 . The method of  claim 42 , wherein (a) and (b) are performed periodically. 
     
     
         44 . The method of  claim 43 , wherein (a) and (b) are performed at adjustable time intervals. 
     
     
         45 . The method of  claim 42 , wherein (a) and (b) are performed intermittently. 
     
     
         46 . The method of  claim 44 , wherein the time interval is not greater than 150 μs.